Biology: Definition and Cell Theory
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Questions and Answers

What is the primary function of the ribosomes in a cell?

  • Regulation of molecule passage
  • Storage of genetic material
  • Synthesis of proteins (correct)
  • Energy production

    • Which statement accurately describes prokaryotic cells?

  • They are more complex than eukaryotic cells.
  • They possess a nucleus and membrane-bound organelles.
  • They have a higher surface area-to-volume ratio than eukaryotes.
  • Their DNA is found in a single circular molecule. (correct)

    • What distinguishes plant cells from animal cells?

  • Presence of chloroplasts (correct)
  • Presence of centrioles
  • Presence of flagella
  • Presence of lysosomes

    • What do all living organisms have in common according to cell theory?

    <p>They are made up of cells.</p> Signup and view all the answers

    Which structure is primarily responsible for performing cellular respiration in a eukaryotic cell?

    <p>Mitochondria</p> Signup and view all the answers

    Which of the following describes a key characteristic of eukaryotic cells?

    <p>They have a complex structure with organelles.</p> Signup and view all the answers

    What is the role of the nucleolus within the nucleus?

    <p>Assembles ribosomes</p> Signup and view all the answers

    What characteristic is NOT associated with multicellular organisms?

    <p>They only reproduce asexually.</p> Signup and view all the answers

    What is produced during noncyclic electron flow?

    <p>ATP and NADPH</p> Signup and view all the answers

    What occurs during cyclic electron flow?

    <p>Recycling of electrons to generate more ATP</p> Signup and view all the answers

    Which step in the Calvin cycle represents the fixation of carbon dioxide?

    <p>Adding CO₂ to ribulose bisphosphate</p> Signup and view all the answers

    Which component is the final electron acceptor in photophosphorylation?

    <p>NADP+</p> Signup and view all the answers

    What is the purpose of creating a proton gradient during the light reactions?

    <p>To drive the synthesis of ATP</p> Signup and view all the answers

    What type of energy conversion occurs in the light reactions of photosynthesis?

    <p>Solar to chemical</p> Signup and view all the answers

    How many molecules of ATP and NADPH are consumed per CO₂ fixed in the Calvin cycle?

    <p>2 ATP and 2 NADPH</p> Signup and view all the answers

    What is a by-product of water splitting in Photosystem II?

    <p>Oxygen</p> Signup and view all the answers

    Why is cyclic electron flow important for the Calvin cycle?

    <p>It provides a higher ATP to NADPH ratio</p> Signup and view all the answers

    Where does the Calvin cycle take place within the plant cell?

    <p>Chloroplast stroma</p> Signup and view all the answers

    Which microscopy technique would provide the highest resolution images?

    <p>Transmission electron microscopy</p> Signup and view all the answers

    What is the primary function of the rough endoplasmic reticulum (ER)?

    <p>Protein modification and folding</p> Signup and view all the answers

    Which structure is key for conducting photosynthesis in plant cells?

    <p>Chloroplasts</p> Signup and view all the answers

    Which component of the cytoskeleton is primarily involved in muscle movements?

    <p>Microfilaments</p> Signup and view all the answers

    What process involves the movement of materials into the cell through vesicles?

    <p>Endocytosis</p> Signup and view all the answers

    Which type of intercellular junction prevents fluid leakage between animal cells?

    <p>Tight junctions</p> Signup and view all the answers

    What is the role of the Golgi apparatus in the cell?

    <p>Modification and packaging of proteins</p> Signup and view all the answers

    Which statement accurately describes the role of ribosomes?

    <p>Facilitate protein synthesis</p> Signup and view all the answers

    During which phase of meiosis does crossing over occur?

    <p>Prophase I</p> Signup and view all the answers

    What is the primary purpose of meiosis in sexually reproducing organisms?

    <p>To create genetically diverse gametes</p> Signup and view all the answers

    Which component of the plasma membrane contributes to its fluidity?

    <p>Cholesterol</p> Signup and view all the answers

    What measurement unit is commonly used for measuring microscopic structures?

    <p>Micrometres (µm)</p> Signup and view all the answers

    Which of the following is a component of the endomembrane system?

    <p>Plasma membrane</p> Signup and view all the answers

    What occurs during Prophase I of meiosis?

    <p>Chromosomes condense and crossing-over happens.</p> Signup and view all the answers

    What does independent assortment during meiosis lead to?

    <p>Diverse combinations of maternal and paternal chromosomes.</p> Signup and view all the answers

    What is the primary outcome of meiosis?

    <p>Four genetically distinct haploid cells.</p> Signup and view all the answers

    Which process enhances genetic diversity by exchanging genetic material?

    <p>Crossing over</p> Signup and view all the answers

    What happens during Anaphase I of meiosis?

    <p>Homologous chromosomes are separated.</p> Signup and view all the answers

    How does meiosis differ from mitosis?

    <p>Meiosis involves two rounds of cell division.</p> Signup and view all the answers

    What is synapsis in the context of meiosis?

    <p>The pairing of homologous chromosomes.</p> Signup and view all the answers

    What role do chiasmata play during meiosis?

    <p>They are points of crossing-over during homologous chromosome exchange.</p> Signup and view all the answers

    Why is genetic variation important for evolution?

    <p>It aids in natural selection and adaptation.</p> Signup and view all the answers

    What is a bivalent in the context of meiosis?

    <p>A pair of homologous chromosomes.</p> Signup and view all the answers

    Which phase of meiosis takes the most time and involves complex events?

    <p>Prophase I</p> Signup and view all the answers

    What ensures that gametes receive a unique set of chromosomes during meiosis?

    <p>Crossing-over and independent assortment.</p> Signup and view all the answers

    What is the significance of reducing chromosome number during meiosis?

    <p>It maintains stable chromosome numbers across generations.</p> Signup and view all the answers

    Which mechanism produces ATP through the direct transfer of a phosphate group from a substrate to ADP?

    <p>Substrate-level phosphorylation</p> Signup and view all the answers

    What is the primary role of NADH in cellular metabolism?

    <p>It facilitates the transfer of electrons in metabolic pathways.</p> Signup and view all the answers

    What is the primary difference between oxidative and photophosphorylation?

    <p>Oxidative phosphorylation occurs during cellular respiration, while photophosphorylation occurs during photosynthesis.</p> Signup and view all the answers

    In which direction does DNA polymerase synthesize the new DNA strand?

    <p>5' to 3'</p> Signup and view all the answers

    How do Okazaki fragments form during DNA replication?

    <p>By discontinuous synthesis on the lagging strand.</p> Signup and view all the answers

    What is a promoter in the context of transcription?

    <p>The sequence where RNA polymerase binds to initiate transcription.</p> Signup and view all the answers

    Which of the following statements is correct regarding the central dogma of molecular biology?

    <p>It describes the sequence of information transfer as DNA → RNA → Protein.</p> Signup and view all the answers

    What is the purpose of RNA processing in eukaryotic cells?

    <p>To modify mRNA for translation efficiency.</p> Signup and view all the answers

    Which enzyme is responsible for unwinding the DNA double helix during replication?

    <p>DNA helicase</p> Signup and view all the answers

    What characterizes the genetic code?

    <p>It is universal but shows some bias in codon usage.</p> Signup and view all the answers

    What role do enzymes play in the activation energy of reactions?

    <p>They lower the activation energy, enhancing reaction rates.</p> Signup and view all the answers

    In eukaryotic cells, where does transcription occur?

    <p>Nucleus</p> Signup and view all the answers

    What is the significance of feedback inhibition in metabolic pathways?

    <p>It prevents the overproduction of metabolites by regulating enzyme activity.</p> Signup and view all the answers

    What is the primary role of ribosomal RNA (rRNA) in ribosomes?

    <p>To catalyze peptide bond formation</p> Signup and view all the answers

    In which site of the ribosome does the charged tRNA enter during translation?

    <p>A site</p> Signup and view all the answers

    Which type of mutation leads to the creation of a stop codon?

    <p>Nonsense mutation</p> Signup and view all the answers

    What is the primary component of the chloroplasts that allows for light energy absorption?

    <p>Thylakoids</p> Signup and view all the answers

    What role does the release factor play in translation termination?

    <p>It cleaves the peptide chain</p> Signup and view all the answers

    In which cellular compartment does glycolysis occur?

    <p>Cytoplasm</p> Signup and view all the answers

    Which of the following best describes the process of chemiosmosis in chloroplasts?

    <p>The pumping of protons to create a gradient that drives ATP synthesis</p> Signup and view all the answers

    What is the main product of the light-dependent reactions of photosynthesis?

    <p>NADPH and ATP</p> Signup and view all the answers

    What is the correct sequence of events in the stages of translation?

    <p>Initiation, Elongation, Termination</p> Signup and view all the answers

    What is the main purpose of the G2 phase in the eukaryotic cell cycle?

    <p>Final preparations for mitosis and organelle duplication</p> Signup and view all the answers

    What initiates the process of photosynthesis in plants?

    <p>Absorption of light energy</p> Signup and view all the answers

    What occurs during anaphase of mitosis?

    <p>Sister chromatids are pulled apart to opposite poles</p> Signup and view all the answers

    The inner mitochondrial membrane forms structures that increase surface area. What are these structures called?

    <p>Cristae</p> Signup and view all the answers

    Which absorbed light wavelengths do chlorophyll pigments primarily use for photosynthesis?

    <p>Violet, blue, and red</p> Signup and view all the answers

    Which of the following structures is crucial for spindle formation during mitosis?

    <p>Centrosome</p> Signup and view all the answers

    How do prokaryotic cells primarily divide?

    <p>Binary fission</p> Signup and view all the answers

    Which component of the electron transport chain is responsible for splitting water molecules?

    <p>Photosystem II</p> Signup and view all the answers

    What is produced during the energy liberation phase of glycolysis?

    <p>ATP and NADH</p> Signup and view all the answers

    What is a significant outcome of the origin of oxygenic photosynthesis?

    <p>Formation of the ozone layer</p> Signup and view all the answers

    What is the definition of Gibbs free energy in a cellular context?

    <p>Energy available for work at constant temperature and pressure</p> Signup and view all the answers

    What characterizes exergonic reactions?

    <p>They release energy</p> Signup and view all the answers

    Which process describes the role of enzymes?

    <p>Lowering activation energy to accelerate reactions</p> Signup and view all the answers

    Why is the endosymbiotic theory significant for mitochondria and chloroplasts?

    <p>They originated from engulfed prokaryotic cells supporting eukaryotic complexity</p> Signup and view all the answers

    What is a defining feature of viruses that makes them distinct from living organisms?

    <p>They lack metabolic processes</p> Signup and view all the answers

    Which characteristic is true regarding the phases of the eukaryotic cell cycle compared to prokaryotic cell division?

    <p>Eukaryotes involve mitosis while prokaryotes do not</p> Signup and view all the answers

    What role does the cleavage furrow play in cell division?

    <p>It divides the cytoplasm in animal cells during cytokinesis</p> Signup and view all the answers

    What effect does the second law of thermodynamics have on energy transformations?

    <p>They lead to an increase in disorder or entropy</p> Signup and view all the answers

    What is the primary energy carrier within cells?

    <p>ATP</p> Signup and view all the answers

    Study Notes

    Biology: Definition and Origins

    • Biology is the scientific study of living organisms (plants, animals, and humans).
    • The term originates from the Greek words "bio" (life) and "logy" (study).

    Cell Theory

    • All living organisms are composed of cells.
    • Cells are the basic units of structure and function in organisms.
    • New cells arise only from pre-existing cells.
    • Key contributors include Schleiden, Schwann, and Virchow (19th century).
    • Antoine van Leeuwenhoek first observed microorganisms.
    • Robert Hooke coined the term "cell" in 1665.

    Understanding Organisms

    • Unicellular organisms consist of a single cell (e.g., bacteria).
    • Multicellular organisms are composed of many cells (e.g., humans, plants).
    • "Organum" is the Latin term for organism, highlighting its structure.

    Cell Structure and Types

    • All cells contain plasma membrane, DNA, and ribosomes.
    • DNA and RNA are essential for protein synthesis and cell function.

    Prokaryotic Cells

    • Simple cells lacking a nucleus and membrane-bound organelles.
    • Shapes include spherical, rod-like, and spiral.
    • DNA is a single circular molecule.
    • Cell walls and flagella/pili aid movement and attachment.

    Eukaryotic Cells

    • Complex cells with a nucleus and membrane-bound organelles.
    • More specialized for complex tasks.
    • Eukaryotic cells have a lower surface area-to-volume ratio than prokaryotic cells.

    Eukaryotic Cell Structures and Functions

    • Cytoplasm: Contains organelles for energy, synthesis, storage, and transport.
    • Ribosomes: Free or attached, involved in protein synthesis.
    • Endomembrane System: Includes nuclear envelope, ER, Golgi, lysosomes, and plasma membrane for protein synthesis and transport.
    • Mitochondria: Perform cellular respiration, producing ATP.
    • Cytoskeleton: Provides structural support, movement, and cell organization.

    Plant vs. Animal Cells

    • Animal cells: Contain lysosomes, centrioles, and flagella.
    • Plant cells: Contain chloroplasts, central vacuole, tonoplast, and a cell wall, reflecting their different functions.

    The Nucleus in Eukaryotic Cells

    • Functions: Contains most of the cell's DNA.
    • Structure:
      • Surrounded by a nuclear envelope with pores regulating molecule passage.
      • Nucleolus assembles ribosomes.
      • Chromatin forms chromosomes.

    Microscopy Techniques

    • Light microscopes use light for viewing specimens (e.g., bright-field, differential interference contrast, fluorescence).
    • Electron microscopes use electrons for higher resolution images (e.g., transmission and scanning electron microscopy).
    • Measurement units: µm (micrometers), nm (nanometers), and Å (angstroms).

    Common Cell Elements

    • Plasma membrane: Surrounds the cell, regulates substance flow (phospholipid bilayer).
    • Cytoplasm: Contains organelles, site of metabolic processes.
    • Chromosomes: Contain genetic material.
    • Cytoskeleton: Provides structural integrity, facilitates cell movement.

    Ribosomes

    • Composition: Ribosomal RNA (rRNA) and proteins make up ribosomes.
    • Function: Protein synthesis, located in cytosol or attached to the endoplasmic reticulum.
    • Subunits: Large and small subunits work together in protein synthesis.

    Endomembrane System

    • Components: Nuclear envelope, ER, Golgi apparatus, lysosomes, vacuoles, plasma membrane.
    • Function: Coordinates protein synthesis, modification, and transport.

    Endoplasmic Reticulum (ER)

    • Smooth ER: Synthesizes lipids, regulates carbohydrate metabolism.
    • Rough ER: Modifies and folds proteins, contains ribosomes.

    Golgi Apparatus

    • Structure: Flattened membranous sacs (cisternae).
    • Function: Modifies ER products, synthesizes macromolecules; sorts and packages proteins.

    Mitochondria and Chloroplasts

    • Mitochondria: Perform cellular respiration, ATP production.
    • Chloroplasts: Found in plant cells, conduct photosynthesis, produce food.

    Peroxisomes

    • Function: Involved in lipid metabolism, detoxification.

    Cytoskeleton and Cellular Movements

    • Cytoskeleton: Network of fibers organizing cell structures and activities.
      • Microtubules: Cell division, movement.
      • Centrosomes and Centrioles: Organize microtubules, cell division.
      • Microfilaments (actin): Muscle movements, cell division, cytoplasmic streaming.

    Extracellular Components and Connections

    • Extracellular structures: Cells produce materials outside the plasma membrane.
      • Plant cell walls: Provide structural support.
      • Animal extracellular matrix (ECM): Structural, biochemical support to cells.
      • Intercellular junctions: Facilitate cell communication, physical contact. (Tight junctions, gap junctions, desmosomes in animal; plasmodesmata in plants)

    Intercellular Junctions

    • Plant plasmodesmata: Membrane-lined pores enabling communication and transport of small molecules.
    • Animal cell junctions:
      • Tight junctions: Prevent fluid leakage.
      • Desmosomes: Anchor cells, maintain structure.
      • Gap junctions: Provide channels for cell communication.

    Fluid Mosaic Model

    • Plasma membrane: Separates cells from surroundings, selectively permeable.
      • Structure: Phospholipid bilayer, embedded proteins.
        • Phospholipids: Hydrophilic heads, hydrophobic tails (bilayer).
        • Membrane proteins: Integral (spanning membrane), peripheral (surface attached), involved in transport, enzymatic activity, signal transduction, and cell recognition.
        • Membrane fluidity: Cholesterol maintains stability, varies with temperature.

    Transport Mechanisms

    • Passive transport: Movement with a concentration gradient without energy. (Diffusion, facilitated diffusion, osmosis)
    • Active transport: Movement against concentration gradient requiring energy. (Primary, secondary active transport, e.g., sodium-potassium pump)
    • Bulk transport: Movement of large materials. (Exocytosis, endocytosis)

    Definitions of Cellular Structures

    • Cell: Smallest functional unit of life.
    • Nucleic acids: Carry genetic information (DNA/RNA).
    • Cell membrane: Regulates cell's internal environment.
    • Cell wall: Protection, support (plant cells).
    • Gene: Segment of DNA, blueprint for traits.

    Cellular Functions and Organelles

    • Organelles: Specialized structures performing functions (ATP production, protein synthesis, cell structure).

    Meiosis: Overview and Importance

    • Meiosis: Cell division in sexually reproducing organisms, reducing chromosome number to form gametes (sperm/eggs).
    • Significance: Ensures genetic diversity and stable chromosome number across generations.

    Stages of Meiosis

    • Meiosis I: Separates homologous chromosomes into two haploid cells.
    • Meiosis II: Separates sister chromatids into four haploid cells. Key phases for both are included.

    Key Terminology in Meiosis

    • Gametes (sperm/eggs): Haploid reproductive cells.
    • Zygote: Fertilized egg; restores diploid number.
    • Bivalent: Homologous chromosome pair.
    • Tetrad: Four chromatids during Prophase I.
    • Crossing Over: Genetic material exchange during Prophase I.
    • Haploid: Half the normal chromosome number.

    Mechanisms of Genetic Variation

    • Genetic variation primarily arises from crossing over and independent assortment in meiosis.
      • Crossing Over during Prophase I: Creates new allele combinations.
      • Independent Assortment during Metaphase I: Maternal/paternal chromosome combinations vary.

    Significance of Genetic Variation

    • Natural selection enables populations to adapt to changing environments.
    • Used in agriculture for resilient crop breeding.
    • Important for personalized medicine, understanding hereditary diseases.
    • Crucial for conservation efforts.

    Definition and Importance of Meiosis

    • Meiosis: Specialized cell division reducing chromosome number, creating four distinct haploid cells (gametes). Essential for sexual reproduction, increasing diversity.

    Stages of Meiosis

    • Meiosis I: Homologous chromosomes separated, resulting in two haploid cells.
    • Meiosis II: Similar to mitosis (separates sister chromatids), creating four haploid cells.

    Major Events and Their Significance:

    • Crossing-over, chiasmata, synapsis, independent assortment are detailed.

    Comparison of Meiosis and Mitosis

    • Mitosis produces two identical diploid cells.
    • Meiosis produces four unique haploid cells.

    Overview of the Cell Cycle

    • Cell cycle: Series of events leading to cell division (growth, DNA replication, chromosome distribution).
    • Phases: G1, S, G2, M (mitosis).
    • Regulation: Checkpoints preventing errors. Cancer results from cycle disruptions.

    Phases of the Eukaryotic Cell Cycle

    • G1: Growth, preparing for DNA replication.
    • S: DNA replication (doubling genetic material).
    • G2: Further growth, organelle duplication.
    • M: Mitosis and cytokinesis.

    Comparison of Prokaryotic and Eukaryotic Cell Cycles

    • Prokaryotes use binary fission (simpler).
    • Eukaryotes have a complex cycle with specific phases.
    • Prokaryotic chromosomes are circular; eukaryotic are linear.

    Key Structures in Cell Division

    • Spindle apparatus
    • Centrosome
    • Kinetochore
    • Cleavage furrow (animal cells)
    • Cell plate (plant cells)

    Stages of Mitosis, in detail

    • Prophase
    • Prometaphase
    • Metaphase
    • Anaphase
    • Telophase

    Key Characteristics of Living Organisms

    • Order
    • Sensitivity
    • Reproduction
    • Growth and Development
    • Regulation
    • Homeostasis

    Characteristics of Viruses

    • Not true living organisms (lack metabolic processes, cannot independently reproduce).
    • Structure: Protein coat surrounding DNA or RNA.
    • Dependence on hosts.
    • Controversy exists about their definition of life.

    Theories on Life's Origins

    • Oparin-Haldane Theory
    • Miller-Urey Experiment
    • Hypotheses on early environments (reducing atmosphere, deep-sea vents, extraterrestrial origins)

    Significance of Oxygenic Photosynthesis

    • Originated with cyanobacteria.
    • Changed Earth's atmosphere by producing oxygen.
    • Enabled aerobic respiration, more complex life.

    The Rise of Oxygen

    • Facilitated aerobic respiration, enabled complex life.
    • Reshaped ecosystems, ozone layer.

    Origin of Mitochondria and Chloroplasts

    • Endosymbiotic theory (engulfed prokaryotic cells).
    • Evidence (double membranes, circular DNA).
    • Evolutionary significance in eukaryotic cell complexity.

    Energy

    • Capacity to do work, various forms (kinetic, potential, chemical, thermal).

    The Laws of Thermodynamics

    • First Law: Energy conservation.
    • Second Law: Entropy increases.

    Cellular Metabolism

    • Overview: Catabolic, anabolic reactions.
    • Energy balance maintains homeostasis.

    Gibbs Free Energy

    • Quantifies work potential in systems.
    • Exergonic and endergonic reactions.

    Role of Enzymes

    • Lower activation energy to speed up reactions.
    • Specificity to substrates.
    • Factors influence activity (pH, temperature).

    Enzyme Cofactors and Coenzymes

    • Cofactors: Inorganic ions.
    • Coenzymes: Organic molecules assisting enzymes.
    • Prosthetic groups: Permanently attached cofactors.

    ATP as an Energy Currency

    • ATP: Primary energy carrier.
    • Hydrolysis: Releases energy (ATP→ADP).

    Mechanisms of ATP Generation

    • Substrate-level phosphorylation
    • Chemiosmosis (electron transport)

    Overview of Bioenergy Carriers

    • ATP: Main carrier.
    • Electron transport linked to ATP synthesis.

    Types of Phosphorylation

    • Oxidative Phosphorylation (mitochondria)
    • Photophosphorylation (chloroplasts)

    Redox Reactions in Energy Transfer

    • Definition (oxidation/reduction, electron transfer).
    • Example (methane combustion).
    • Importance in ATP production (glycolysis, citric acid cycle).

    Key Electron Carriers

    • NAD⁺, NADH, NADP⁺, FAD, FADH₂, cytochromes.
    • Function: Facilitating electron transfer in metabolic pathways.

    Energy of Activation

    • Minimum energy needed for a chemical reaction.
    • Enzymes lower activation energy.

    Role of Enzymes in Metabolism

    • Catalysts accelerating reactions.
    • Specificity to substrates.
    • Regulation through feedback and allosteric methods.

    DNA Replication Overview

    • Process: Copying DNA to produce two identical molecules.
      • Semiconservative Replication: One parental strand, one new strand in each new molecule. (Meselson-Stahl experiment).

    Semi-conservative Replication Process

    • Untwisting the helix (hydrogen bonds broken).
    • Strand Separation.
    • DNA polymerase adds nucleotides.
    • Lagging strand: Okazaki fragments, joined by DNA ligase.

    Key Enzymes and Proteins

    • DNA helicase
    • DNA polymerase
    • Topoisomerase
    • DNA ligase
    • Single-stranded binding proteins
    • DNA primase
    • DNA clamp

    Replication Origin

    • Bacteria (single origin).
    • Eukaryotes (multiple origins).

    Gene Expression

    • Process: DNA → RNA → Protein (central dogma).
    • One Gene-One Enzyme Hypothesis (Beadle & Tatum): Each gene controls a specific enzyme.

    Transcription

    • Copying DNA into RNA (mRNA for proteins, ncRNA).
    • Prokaryotes: Transcription & translation in cytoplasm.
    • Eukaryotes: Transcription in nucleus, translation in cytoplasm.
    • Gene components: Promoter, regulatory sequences, transcribed region, terminator.

    The Genetic Code

    • Codons (3-nucleotide sequences) specify amino acids.
    • Start codon (AUG), stop codons (UAA, UGA, UAG). Redundant but not ambiguous. Universal.

    Translation

    • mRNA decoded by ribosomes to form a polypeptide (protein).
    • Ribosome sites: A, P, E.
    • tRNA carries amino acids, anticodon pairs with mRNA codons.
    • Aminoacylation: Attaching amino acids to tRNA.

    Gene Mutations

    • Permanent DNA sequence changes.
      • Base substitutions (missense, silent, nonsense).
      • Frameshift mutations (insertions/deletions).

    Ribosome Structure and Function

    • Ribosomes (30S/50S): tRNA-binding sites (A, P, E). rRNA, not protein, catalyzes peptide bond formation.

    Translation (Protein Synthesis)

    • Initiation: mRNA binding, formation of initiation complex
    • Elongation: Codon reading, peptide bond formation
    • Termination: Stop codon recognition, release of polypeptide chain

    Bioenergetics

    • Photosynthesis (chloroplasts)
    • Cellular Respiration (mitochondria)

    Mitochondrion Function

    • Location of aerobic respiration and ATP production.
    • Double membrane, cristae (inner membrane folds).

    Stages of Cellular Respiration

    • Glycolysis (breakdown of glucose)

    Chloroplast Structure

    • Stroma (fluid)
    • Thylakoid membranes
    • Granum (stacks of thylakoids)

    Light Energy and Photosynthesis

    • Light composition
    • Wavelengths absorbed by plant pigments

    Photosynthetic Pigments

    • Chlorophyll (a, b)
    • Carotenoids

    Photosystems

    • Light-harvesting complex (antenna complexes)
    • P700 (Photosystem I)
    • P680 (Photosystem II)

    Electron Transport

    • Water splitting, oxygen release.
    • Electron chain from PSII to PSI.
    • Proton gradient generation.

    Chemiosmosis (Photophosphorylation)

    • ATP synthesis powered by proton gradient.

    Noncyclic and Cyclic Electron Flow

    • Noncyclic: ATP & NADPH production.
    • Cyclic: More ATP production.

    ATP and NADPH Production

    • Chemical energy from converting light energy.
    • Used in the Calvin Cycle

    Carbon Fixation (Calvin Cycle)

    • Stroma location
    • CO₂ fixation by Rubisco
    • G3P generation, sugar production

    Products of Photosynthesis

    • ATP, NADPH, & Oxygen.
    • G3P: Starch, amino acids, fatty acids, sucrose.
    • Light-Dependent reactions (light reactions), Light Independent reactions (Calvin Cycle)

    Final Electron Acceptors

    • Photophosphorylation: NADP⁺
    • Oxidative Phosphorylation: Oxygen

    Noncyclic Electron Flow

    Cyclic Electron Flow

    Comparison of photophosphorylation and oxidative phosphorylation

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